This invention relates to making connections between integrated circuit array packages (IC) and circuit boards.
Ball grid array (BGA) and land grid array (LGA) packages are becoming increasingly popular because of their low profiles and high densities. With a BGA package, for example, the rounded solder balls of the BGA are generally soldered directly to corresponding surface mount pads of a printed circuit board rather than to plated thru-holes which receive pins from, for example, a pin grid array IC package.
Sockets are used to allow particular IC packages to be interchanged without permanent connection to a circuit board. More recently, sockets for use with BGA and LGA packages have been developed to allow these packages to be non-permanently connected (e.g., for testing) to a circuit board. However, problems can exist in attaching a BGA package to conventional sockets. This is because a BGA package presents a non-traditional mating condition. The rounded solder balls of the BGA are themselves relatively poor points of contact for socketing, suited only for their intended purpose of being reflowed. Further, the co-planarity between the individual points of contact for each rounded solder ball may be lacking due to ball irregularities and warping of the BGA package.